StatelessService.RunAsync(CancellationToken) Method

Definition

Namespace:

Microsoft.ServiceFabric.Services.Runtime

Assembly:

Microsoft.ServiceFabric.Services.dll

Package:

Microsoft.ServiceFabric.Services v6.1.1583

Services that want to implement a background task, which runs when the service comes up, should override this method with their logic.

For information about Reliable Services life cycle please see https://docs.microsoft.com/azure/service-fabric/service-fabric-reliable-services-lifecycle

protected virtual System.Threading.Tasks.Task RunAsync (System.Threading.CancellationToken cancellationToken);

abstract member RunAsync : System.Threading.CancellationToken -> System.Threading.Tasks.Task
override this.RunAsync : System.Threading.CancellationToken -> System.Threading.Tasks.Task

Protected Overridable Function RunAsync (cancellationToken As CancellationToken) As Task

Parameters

cancellationToken

CancellationToken

Cancellation token to monitor for cancellation requests.

Returns

Task

A Task that represents outstanding operation.

Remarks

Please ensure you follow these guidelines when overriding RunAsync(CancellationToken):

• Make sure cancellationToken passed to RunAsync(CancellationToken) is honored and once it has been signaled, RunAsync(CancellationToken) exits gracefully as soon as possible. Please note that if RunAsync(CancellationToken) has finished its intended work, it does not need to wait for cancellationToken to be signaled and can return gracefully.
• Service Fabric runtime does not handle all exception(s) escaping from RunAsync(CancellationToken). If an unhandled exception escapes from RunAsync(CancellationToken), then Service Fabric runtime takes following action(s):
  • If a FabricException (or one of its derived exception) escapes from RunAsync(CancellationToken), Service Fabric runtime will drop this service instance and a new instance will be created. Furthermore, a health warning will appear in Service Fabric Explorer containing details about unhandled exception.
  • If an OperationCanceledException escapes from RunAsync(CancellationToken) and Service Fabric runtime has requested cancellation by signaling cancellationToken passed to RunAsync(CancellationToken), Service Fabric runtime handles this exception and considers it as graceful completion of RunAsync(CancellationToken).
  • If an OperationCanceledException escapes from RunAsync(CancellationToken) and Service Fabric runtime has NOT requested cancellation by signaling cancellationToken passed to RunAsync(CancellationToken), the process that is hosting this service instance is brought down. This will impact all other service instances that are hosted by the same process. The details about unhandled exceptions can be viewed in Windows Event Viewer.
  • If an exception of any other type escapes from RunAsync(CancellationToken) then the process that is hosting this service instance is brought down. This will impact all other service instances that are hosted by the same process. The details about unhandled exceptions can be viewed in Windows Event Viewer.

Failing to conform to these guidelines can cause fail-over, reconfiguration or upgrade of your service to get stuck and can impact availability of your service.